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People v. Cooper.

2021 CO 69. No. 19SC249. Admissibility of Expert Testimony—CRE 702—Relevance—Helpfulness to the Jury—“Fit”—Generalized Expert Testimony—Sufficient Logical Connection to the Facts to be Helpful to the Jury—CRE 403 Admissibility—Domestic Violence Expert Testimony—Power and Control Dynamic—Power and Control Wheel.

September 27, 2021


Before expert testimony is admitted into evidence, a trial court must find that it would be helpful to the jury. Whether expert testimony is helpful to the jury hinges on “fit”—the expert testimony must fit the case. Here, the Supreme Court considered how close a fit is required.

The Court held that generalized expert testimony fits a case if it has a sufficient logical connection to the factual issues to be helpful to the jury while still clearing the ever-present CRE 403 admissibility bar. In evaluating the fit of generalized expert testimony, a trial court must be mindful of the purposes for which such testimony is offered—that is, the reasons why the proponent of the evidence has asked the expert to educate the jury about certain concepts or principles.

Here, the trial court restricted the generalized expert testimony offered by the People regarding the dynamics of domestic violence. After considering the victim’s testimony, the proposed expert opinions, and the reasons why the People were seeking to educate the jury, the trial court allowed only those opinions that it viewed as having a sufficient logical relation to the facts to be helpful to the jury without violating CRE 403. Because the trial court properly exercised its discretion in carrying out its gatekeeping function, and because the standard of review pertaining to the admission of expert testimony is highly deferential, the Court of Appeals erred in reversing the judgment of conviction.

The Court of Appeals adopted a fit standard that is inflexible and overly exacting. While generalized expert testimony must fit the case, the fit need not be perfect; each aspect of such testimony need not match a factual issue. Because generalized expert testimony, by definition, seeks to inform the jury about generic concepts or principles without knowledge of the facts, it is almost inevitable that parts of such testimony will not be logically connected to the case. For that reason, the fit inquiry must be flexible. A trial court should not be expected to parse the proposed testimony and determine whether each statement the expert intends to utter is logically connected to a fact in the case. If the generalized expert testimony’s logical connection to the factual issues is sufficient to be helpful to the jury without running afoul of CRE 403, the testimony fits the case.

Still, attorneys and trial courts should do their best to avoid introducing generalized expert testimony that has no logical connection to the case facts. As relevant here, prosecutors should take care to endorse generalized expert testimony about domestic violence only in appropriate cases; and, when they do so, they should endeavor to present only testimony that is logically connected to the factual issues. Trial courts, in turn, should exercise their discretion in deciding whether to permit all, some, or none of the proffered testimony under the fit standard articulated here. In doing so, trial courts should consider the feasibility and propriety of admitting only a portion of the proposed generalized expert testimony on a particular subject.

Because the Court of Appeals incorrectly overturned the judgment of conviction, the Court reversed. The case was remanded to the Court of Appeals for further proceedings consistent with this opinion.

Official Colorado Supreme Court proceedings can be found at the Colorado Supreme Court website.

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